Arrangement relating to automoatic telephone systems



Jan. 23, 1934. A. H. oLsoN El' AL.

ARRANGEMENT RELATING TO AUTOMATIC TELEPHONE SYSTEMS Filed Nov. 5, 1932 4Sheets-Sheet l Jan. 23, 1934. A H, OLSON E, AL 1,944,570

ARRANGEMENT RELATING TO AUTOMATIC TELEPHONE SYSTEMS 4 Sheets-Sheet 2Filed NOV. 3, 1932 Axel Heimqn San 5+ Dam'cal Vlarem i NEN-roms 4 @Wwwum Jan. 23, 1934. A OLSON vE -r AL 1,944,570

ARRANGEMENT RELATING To AUTOMATIC TELEPHONE SYSTEMS Filed Nov. 3, 1952 4Sheets-Sheet 3 lNvENToRf,

Jan. 23, 1934. A. H. OLSON ET AL 1,944,570

ARRANGEMENT RELATING TO AUTOMATIC TELEPHONE SYSTEMSl 1932 4 Sheets-Sheet4 Filed Nov. 3?.

Patented Jan. 23, 1934 ARRANGEMENT RELATING TO AUTOMATIC TELEPHONESYSTEMS Axel Herman Olson and Sten Daniel Vigren, Stockholm, SwedenApplication November 3, 1932, Serial No. 640,975, and in Sweden November20, 1931 Claims.

This invention relates to a certain new and useful arrangement forautomatic telephone systems, and the following' is a full, clear andexact description of the same, reference being made to 5 theaccompanying drawings, forming part of this specification.

Our invention has reference to an arrangement for automatic telephonesystems, that makes possible an economic automatic switching betweenvarious telephone plants of different size and varying operatingconditions.

Making rural telephone plants automatic has heretofore caused certaindiiiiculties of economic and technical nature.

These difficulties have specially been observed in such systems, whichcontain several exchanges of diierent sizes, said systems being usuallyre ferred to as star shaped.

In such systems it is economically desirable to employ as few registersas possible and this is specially so in small rural exchanges thatcontain few subscribers. Furthermore, it is desirable,

when registers are employed in intermediate exchanges only, that they beused as little as possible.

The present invention has for its object an arrangement for automatictelephone systems, to permit economical automatic service betweentelephone plants of different kinds and comprising exchanges of varioussizes.

The invention is principally characterized by the fact, that registersand so called exchange group selectors, that is, switching devices forselecting idle trunk lines to other exchanges, are located principallyat exchanges which are arranged for tandem working and by the fact thatthe registers are used only for calls between two or more exchanges.

Another characteristic of the invention is that the exchange groupselectors can be directly operated by impulses from a register. Theexchange group selectors can, however, also be so arranged, that theyare operated by impulses from registers via direction selectors.

The necessary direction selectors are arranged for selection over twoseparate groups of lines, of which one is used for direct connection tonecessary group and line selectors for internal traffic and the otherfor direct connection to exchange group selectors. The directionselectors are so arranged that the sequence in which its groups of linesshall be selected. can be changed by changing the connections of thedirec 55y tion selector.

The advantages of arrangement the invention are manifold:

according to In order to establish a connection between subscribersconnected to the same exchange, only that number of digits need bedialled which corresponds to the size of that exchange, that is,

the number of the subscriber.

If a communication is desired between subscribers connected to differentexchanges, that number of digits should be dialled, which depends partlyupon the exchange of the desired subscriber and the size of saidexchange.

partly upon Another advantage of the invention isthat it permitsso-called cross connections of star shaped plants, that is, directconnections from one exchange to another, should the `exchanges belohgto the same or to diiierent districts. Existing plants can thus be usedand the lines needed for a certain connection can be made shorter thanis now the case in star shaped plants.

The cross connections are of the greatest importance in cases where, forinstance, 'a terminal exchange, a satellite to a larger exchange orso-called junction exchange, has a heavy traiiic with other terminal orjunction exchanges. In such cases it is economically desirable toestablish direct lines so-called cross trac between two. nearbyexchanges belongingY connections. Heretofore,

to different districts, has been directed over the respective districtexchanges. With cross connections, according to the present inventionsuch roundabout ways are avoided. v

This invention provides for a simple time-Q zone-metering. When aregister has accumulated a number corresponding to a certain exchange,said exchange lis definitely determined, Whereby circuits for tollcharges devices can be prepared for completion, when the communicationis established.

The invention is further characterized by the fact that a call lfromoneexchange to another is accumulated in a register which in any knownway transfers and transmits the impulses corresponding to the desirednumber. When the for traic change.

:to a subscriberbelonging to the ex Civ.

Fig. 1 4. show difieren The arrangement of direction selectors andexchange group selectors in series has advantage that group and lineselectors oi an exchange will be used not for tandem working to otherexchanges, but only for internal connections between subscribersbelonging to the same exchange. In axchanges having relatively heavyoutgoing traflic this arrangement makes it possible to build theselecting equipment at a lower total cost than what would be possiblewith arrangements with exchange group selectors without directionnnders.

Even in cases, where the exchange group selectors are used for internalas well as for outgoing and through traiilc, the register devices willbe occupied only for communications via two or more exchanges. Theselectors and the registers are thereiore arranged in such a way, thatcommunications are obtained over one or more exchanges, no matter wheresituated, by dialling the number of the desired subscriber, or adirection number. A tone is received from the register corresponding tothe last exchange number and the number of the desired subscriber. Theconnection or" the registers ior receiving and transmitting dialimpulses is such, that the register is controlled by group selectors orso-called exchange group selectors. The latter are of such aconstruction, that they are used only by establishing communications viaone or several exchanges. Should the communication be extended only overone exchange, the exchange group selectors will be used only once.

Should the communication be extended via two or several exchanges, theexchange group selectors will be used twice. By dialling a so-calleddirection number, the exchange group selectors are connected to aregister and eventually over register selectors in such a way that theexchange group selectors will again be restored to normal position, andthen operated by the rst series of impulses transmitted from theregisters after the transmission of the dial tone. The connection toregisters and register selectors is cut off after the transmission ofall impulses from the corresponding register.

Other characteristics of the invention will appear from the followingdescription in conjunction with the accompanying drawings, of A'whicharrangements according to thel invention. Although the automatic systemis disclosed as applied to cross-oar switches, which can be used as linefinders, direction selectors, line selectors, exchange group selectors,register selectors,k registers, etc., it can be used also in combinationwith other types of switches. When a terminal exchange with step-by-stepselectors is connected to a system according to this invention, nochanges are necessary in such a terminal exchange.

One of the principal advantages of the system according to thisinvention is `that trunks or junction lines, selectors and registers arenot made busy before they are really needed for es= tablishing aconnection. The dial impulses op erate the selectors directly as long assuch a proceeding is desirable and suitable to a uniform numberingscheme. Registers are introduced only when really needed, that is, whena call The first cost will be reduced to a minimum.

Fig. 1 shows the arrangement, according to which the transmission ofimpulses from registers is directedl via direction selectors to* .ex-.change group selectors, etc., while Fig. 2 shows exchange groupselectors directly connected to register connecting devices or registerpreselectors and by which arrangement direction selectors will be lessused, than according to the arrangement shown in Fig. 1. Figs. 3 and 4show special forms of arrangements according t0 Fig. 2. In Fig. l K13,E19, Kzi and D22 are provided with direction selectors in addition tothe exchange group selectors, only exchange Kw being provided with thelatter. This ngure is intended to show the flexibility of the system,satisfying different individual traffic requirements oi each exchange.

In Fig. 2 there are no direction selectors of K13, Kao, Km, D22.

The exchange group selectors are in both cases so arranged that they canbe operated directly by impulses transmitted from a register or by theimpulses of a subscribers dial.

According to Fig. 2 a substantial reduction of the number of directionselectors of the whole system is obtained and is specially suitable forthe mechanization of existing rural telephone plants.

The exchange group selectors can be connected directly to directionselectors as per Fig. 1, or to a register via register selector as perFig. 2.

Fig. l contains a number oi circles of which A10, ein, A17 representlterminal exchanges. Kia, Kia, Kei intermediate or junction exchanges,and i322 a district or debiting exchange. The exchanges are providedwith iinders, direction selectors, line selectors, register selectors,registers and exchange group selectors, which are marked S, lV, LV7 ReVand SGV respectively. The junction exchanges Kia, Kan and lszi areprovided .with direction selectors and exchange group selectors forthrough traiiic, while the junction exchange Km is provided with onlyexchange group selectors for both through traiiic and tramo tosubscribers connected to the said junction exchange. y

II" the subscriber 12 of the terminal exchange Aie calls anothersubscriber 20 of the same exchange, the subscriber 12 obtains aconnection to the line selector LV1() over a iinder or preselector Sie,a direction selector RVio and eventually also over a group selector. Thedesired connection is obtained by dialling the number ai) of the desiredsubscriber. Ii the same subscriber l2 desires a connection to asubscriber 93 of the junction exchange Kia, he will obtain in the abovedescribed way a connection to a line selector LV 1o. l-aving received adial tone he dials a special digit,

for instance 0. Y The direction selector RVN) will i be operated so thatthe connection to the group and line selectors of the terminal VexchangeA10 will be cut off and the connectionestablished over the contact l toan outgoing trunk line. When the call arrives to the junction exchangelire if over the contact 2, the subscriber l2 will automatically kobtainconnection over a register selector RcVi to a register R18. 1i the saidregister is disengaged, the subscriber will receive a dial tone, aiterwhich he then may dial the numbers of both the junction exchange and oi'the desired subscriber, in this case 18-93.

rThe register R18 is so connected, that its transmitting device, afterthe dialling of the figures, first will transmit a series of impulseswhich will switch the direction selector RVH; from the conn nection tothe exchange group selector SGViS to the group and line selectors LVN.The other impulses transmitted from the register are sent in any knownway. Y

Should' the subscriber 1'2 desire to call the subscriber 3075 of thedistrict exchange D22, the switching, in order to obtain connection tothe register R18, will be similar to that described above. Uponreceiving the dial tone, the subscriber l2 shall dial the numberscorresponding to the district exchange and to the desired subscriber, inthis case 22-3075. In this case the register R18 will be connected insuch a way, that its transmitting device, when the digits have beendialled, firstly transmits a series of impulses, which operates theexchange group selector SGV18 in order to iind a disengaged trunkline tothe district exchange D22, whereby the contact 3 is closed. The nextseries of impulses operates the direction selector RV22 in order toconnect it to the group and line selector LV22 of the district exchange.The following impulses transmitted from the register will complete theconnection in any known Way.

If the subscriber 12 desires to call the subscriber 77 of the terminalexchange A17, the connection to the register R18 Will be similar to thatdescribed above. After receiving the dial tone, the subscriber 12 dialsthe numbers corresponding to the terminal exchange A17, and to thedesired subscriber, in this case l7-77. The reg.

ister R18 is connected in such a way, that its transmitting device,after dialling, firstly will transmit a series of impulses, to operatethe exchange group selector SGV18 to find a disengaged trunk lineleading to the district exchange D22, whereupon the contact 3 is closed.The next series of impulses operates the exchange group selector SGV22to find a disengaged trunk to the junction exchange K21, whereupon thecontact 6 is closed. The following series of impulses operates theexchange group selector SGV21, to iind a disengaged trunk line to theterminal exchange A17,

whereupon the contact 7 is closed. Other transmitted series of impulsesWill complete the connection to the subscriber 77 in any known way.

If a subscriber 25 of the terminal exchange A18 should desire to callthe subscriber '77 of the terminal exchange A17, the dialling of thesubscriber 25 will be similar to that which will take place, when thesubscriber 12 obtains connection to the subscriber 77, although theconnection will be established over a less number of exchanges.

In order to establish a connection between the subscribers 12 and 44 ofthe terminal exchange A10 and of the terminal exchange A14,respectively, the numbers of both the terminal exchange and of thedesired subscriber must be dialled, in this case 14-44, whereupon aconnection to the register R18 is obtained and dial tone is received.The register R18 is connected in such a way, that its transmissiondevice, after dialling of the numbers, first transmits a series ofimpulses which operates the exchange group selector SGV18 to find adisengaged and direct trunk line to the terminal exchange A14. Otherimpulses transmitted by the register transmission device will completethe connection in any known way.

Ii a subscriber of a junction or of a district exchange, for instancethe subscriber 88 of the junction exchange K18 desires to call thesubscriber 93 of the same exchange, the calling subscriber 88 iirstlyobtains connection to the line f selector LV18 over a iinder orpreselector S18 and eventually also over a group selector. Afterreceiving the dial tone, the number of the desired subscriber isdialled, whereupon the connection will be established.

Should the same subscriber 88y desire tocall another subscriberbelonging to any other exchange, the subscriber 88, having obtainedconnection to a disengaged line selector` LV18 and having received thedial tone, must dial a special digit, for instance 0. The directionselector RVH;` will be operated in such a way, that connections will beobtained both to the exchange group selector SGVia and to the registerR18 over the register selector ReV18.

Having received a dial tone the subscriber 88 will dial the numbers ofboth the exchange and the subscriber and these will be accumulated inthe register. The switching arrangements are in other respects similarto those described above.

Fig. 2 also shows a number of exchanges marked by circles. A10, A11, A17are terminal exchanges, K18, Kw, K21 junction exchanges and D22 adistrict ordebiting exchange. The terminal exchanges are provided withfinders S, direction selectors RV and line selectors LV and the junctionand the district exchanges with iinders S, line selectors LV exchangegroup selectors SGV, register selectors RcV and registers R. Ifnecessary all exchanges can, of course, be provided with preselectorsand group selectors.

Calls between two subscribers belonging to the same exchange, forinstance to the terminal exchange A10, will be established in the sameWay as described in conjunction with the arrangements, shown in Fig. 1.

However, in case of calls between two subscribers belonging to differentexchanges of the same. district or junction exchange, the connectionWill be different.

Ii in the arrangement according to Fig. 2' the subscriber 10 at theterminal exchange A10 de# sires a communication with a subscriber 393 ofthe junction exchange K18, hel obtains in the above described wayconnection to the line selec-- After receiving the dial tone, he dialsfi tor LV10. a special digit for instance 0. The direction selector RV10will be operated in such a manner that the connection to a group andline selector or" the terminal exchange is cut off, and connection to anoutgoing trunk line over the contact 1 is obtained. When thecallarrives'at the junction exchange K18 over ,the contact 2, thesubscriber 10 is automatically connected over a reg.- ister selectorReVis to a register R18. If the register is disengaged, dial tone issent out. The subscriber 10 then dials theY numbers of both the junctionexchange and the desired subscriber, in this case 18393. The registerR18 is so connected that its transmitting device, after theV diallingvof the digits, transmits a series of impulses, which operates theexchange group selectorSGVw, con-A necting it to group or line selectorsLV18.. Other series of impulses complete the connection in the knownway. v

Should the subscriber 10 of terminal exchange A10 desire to call thesubscriber 3075 of the district exchange D22, the connection to theregister R18 will be similar to that described above. After receivingthe dial tone, the subscriber' 10 dials the numbers of both the districtexchange andthe desired subscriber, in this case 22-3075. Ther-Vregister R1a is so connected that its transmitting.` device, afterreceiving the dialled numbers; first transmitsy a series of impulseswhich operates the exchange group selector SGV18 to iind a disen gagedtrunk line to the districtf exchange D22,V

whereuponthecontactisclosed. The next series of impulses operates theexchange g-roupr selector,

SGV22 for connection` to the group or line selector LV22fvof thedistrictexchange.- Other-series of im'` 1 Eil? pulses, transmitted fromthe register, will complete the connection.

vIf the subscriber l() of the terminal exchange A111 desires to call thesubscriber 77 of the terminal exchange A17 the connection to theregister R18 will be similar to what has been described above. Afterreceiving the dial tone the subscriber 10 dials the numbers of both theterminal exchange and of the desired subscriber, in this case 1'7-77.The register R18 is so connected that its transmitting device, afterreceiving the dialled nurnbers, rst transmits a series of impulses tooperate the exchange group selector SGV18 to nnd a disengaged trunk lineto the district exchange D22, whereupon the contact 3 is closed. The

'next series or impulses operates vthe exchange group selector SGVzz tond a disengaged trunk line to the junction exchange K21, whereupon thecontact 5 is closed.

The following series of impulses operates the exchange group selectorSGN/21 to find a disengaged trunk line to the terminal exchange A17,whereupon the contact 7 is closed. Other series of impulses transmittedfrom the register complete the connection to the subscriber 77.

Ii' the subscriber 25 of the terminal exchange A16 desires to call thesubscriber 77 of the terminal exchange A17, the connections will besimilar to those which will take place when the subscriber l0establishes a connection to the subscriber 77, although the connectionwill pass through a lesser number of exchanges.

In order to obtain a connection between the subscriber 10 and thesubscriber 44 of the terminal exchange A14, the numbers of the terminalexchange A14 and that of the desired subscriber must be dialled, in thiscase lli-44 after connection has been made to the register and the dialtone has been obtained. The register R18 is so connected that itstransmitting device, after receiving the dialled numerals, firsttransmits a series of impulses to operate the exchange group selectorSGV18 to find a disengaged trunk line going directly to the terminalexchange A14. Other transmitted series of impulses complete theconnection in any known way.

If a subscriber oi a junction or district exchange, for instance thesubscriber 288 of the junction exchange K11; desires communication withsubscriber 393 of the same exchange, the calling subscriber 288 obtainsconnection to exchange group selector SGVw over a finder or preselectorS13. Having received a dial tone he dials the number of the desiredsubscriber, whereupon the connection is obtained in any known way.

Should the same subscriber 288`desire to call another subscriberbelonging to any other exchange, the subscriber 288, after havingestablished connection to the exchange group selector SGVis, dials aspecial digit, for instance 0. In this Way connection is obtained to aregister R18 over a register selector ReVm. Having received a dial tone,the subscriber 288 dials the numbers of the exchange and of thesubscriber. These numbers are accumulated in the register. The switchingarrangements are in other respects similar to those described above.

Figs. 3 and e show diagrammatically an exchange group selector circuitaccording to the system shown in Fig. 2.

The constuction and the connection of the registers and registerselectors will be alike and independent of the origin and destination ofthe calls as will be clearfrom the following. The

b. Calls extended over two or more exchange group selectors.

c. Calls extended over a direction selector and one or several exchangegroup selectors.

a. Calls extended over only one exchange group selector When forinstance the subscriber 288 belonging to junction exchange K13 desiresto call the subscriber 393 belonging to the same exchange, the firstsubscriber lifts his receiver from the hook whereupon he obtainsconnection to the exchange group selector SGV over a finder orpreselector and the line L (see Fig. 4) over contacts 4 and 7 of relayR1 in the register selector ReV (see Fig. 3).

R10 (Fig. 4) is operated (plus, operating winding of R10, 1R11,conductor a, LiR1, the loop of the subscriber, VH1, conductor b, 3R11,lower Winding of R10, minus). The operation of R10 breaks the contacts2, 3R10 and closes 1R10 in such a manner that. R11 and R12 are operatedin parallel. The circuit or" R11 passes from plus over 1R10, R11 tominus, and that of R12 from plus over 1R10, 2R13, R12 to minus. Theoperation of R11 opens the Contact 3R11 and closes l, 2, i, 5, 6 and7R11. The closing of 4R11 causes the operation of cut oli relay oi thecalling subscriber and busies the corresponding iinder and preselector.The closing oi l, 2R11 makes possible the transmission ci dial tone fromthe buzzer devices SU (SU, 1R13, iR11, the buzzer winding of R10, 2R11,SUj. The buzzer tone is transformed over the operating winding of R10and the wires d and b to the subscriber.

The subscriber after receiving dial tone will dial a special directiondigit, for instance 0, if he desires to call a subscriber connected toanother exchange. In order to explain the operations that occur, whenthe subscriber, after receiving dial tone, dials the digit 8 (oneimpulse), the switching operations at the begining and at the end of theimpulse will be described.

1st impulse starts-R10 is demagnetized on account of the opening of theimpulse contact of the subscribers dial. STB/i0 (Fig. 9) is energized(plus, 2R10, 5R11, 1R12, 3R15, STlVio, minus), whereby 1, 2, fiSTMo areciosed and BSTMO is opened. The closing ci 2STM0 inagnetizes R13 (plus,5R11, R13, 4R13, 2STM11, minus), which receives holding current (plus,6R11, R13, 5R13, minus). When R13 is energized l, 2, 3, 4R13 are openedand 5, 6R13 are closed. The buzzer SU is disconnected.

1st impulse ceases.-R10 is magnetized, when the impulse contact ci thesubscribers dial is closed, STM@ receives holdingY current in serieswith R14, which is magnetized (plus, 6R11, 8R13, 4R14, R14, STT/11,4STMO, SThc, minus) At the end of the iirst impulse R10, R11, R12, R13,R14 and STM@ are niagnetized, R12 on account of its delayed action. Asthe impulse'series now is ended, R12 will be de-energized when the timeof delayed action is over. '2R12 is closed, whereby the bar magnet STM1is magnetized (plus, STD/i1, lORi, d-Wle, 2R12, 3R14, ZSTD/i'o, minus)and 1, 2STM1 are closed.

The hunting for a disengaged trunk from the register selector to aregister', is started, HBRlVi1 is magnetized (plus, HBRMi, 4HBRM2,4HBRM3, 1STM1, minus), whereby 3, 5HBRM1 are closed and 2HBRM1 isopened. The closing of 5HBRM1 causes the testing relay R7 to bemagnetized, if the first trunk from the register selector RdV to aregister is disengaged (plus, 2STM1,R1, SHBRMg, 8HBRM2, 5HBRM1, contactcorresponding to 1R5, minus). 1, 3R7 are opened and 2R7 is closedwhereby R6 is magnetized (plus, Re, 2R7, ISTMO, minus), whereby 1R11 isopened and 2R11 is closed. Re thus receives holding current (plus, Re,2Re, 1STM1, minus), and the hunting for a disengaged outgoing trunkceases. BRD/I1 is magnetized (plus, BRM1, 3HBRM1, 6HBR1VI2, 2Ra, 1STM1,minus), and 3, 4, 5, 6, 7STM1 are closed. The closing of 7STM1magnetizes a relay corresponding to R4 (plus, R4, 7STM1, 11R1, cl-wire,2R12, 3R14, ZSTMU, minus). A contact corresponding to lRi is closed, sothat a relay corresponding to R5 is magnetized and closes two contactscorresponding to 2, SRs. Rv is demagnetized and closes 3R11, so that R1is magnetized. Its circuit will then be as follows (plus, contactcorresponding to 2R11, 1BRM1, holding winding of BRD/I1, 5STM1, R1, 2R1,3R? and minus). 1, 3, 5, 5, 8, 9R are closed and 2, 4, '7, l0, 11R1 areopened, whereby R1 receives holding current (plus, contact correspondingto 2Rs, 1BRM1, holding winding of BRD/I1, 5STM1, R1, 1R1, minus). Thecalling line L is connected to the register R. The opening of 4, 7R1demagnetizes R10 of the exchange group selector, whereby all itscorresponding relays are demagnetized. The closing of 3, SR1 causes thatthe wires u and b or" the calling line L to obtain feeding current over6, '7STM1 from a relay corresponding to R11. The opening of 11R1demagnetizes HBRM1. When a subscriber thus, after dialing the digit 0,has obtained connection to a disengaged register over a registerselector, BRM1, R1 and two relays corresponding to V,R4 and R5 are theonly relays, that remain magnetized.

Should the first line outgoing from the register selector ReV beengaged, R7 cannot be magnetized, 1R7 remains closed in this case,whereby HBRM2 is magnetized and opens the circuit of HBRM1. Should alsothe second outgoing line be engaged, HBRM3 is then magnetized, etc.Should all outgoing lines be occupied, HBRMs connects HBRM1, whereuponthe hunting starts again.

From the foregoing it will be clear that, when a line L is connected toa disengaged register, one BRM relay and two relays corresponding to R4and R5 are the only ones that remain energized. The closing of 9R1busies the previously used eX- change group selector SGV, because plusis connected to its c-wire.

For the sake of nsimplicity let us assume that BRD/I3 is magnetizdinstead oi BRD/I1. The line L thus obtains its feeding current from there lay R4 over the contacts 16, i'lSTM1. rThe closing of 1R4 magnetizesR5 (plus, 1R11, R5, minus), whereby SRs is closed and buzzer tone istransformed to R4 and the line L. Having received a second dial tone thesubscriber dials the numbers of the exchange and of the subscriber,which are accumulated in the register to be retransmitted later. Beforethe transmission device of the register transmits the impulses necessaryfor the setting of the diiierent selectors, lRs is closed. This happensafter the subscriber has dialled one or several digits and causes R2 tobe connected to the wires a and b attached to the exchange groupselector SGV over 13, 14STM1 and 5, 8R1. When the series of impulsesfrom the register are transmitted, 1R2 is closed and opened in the sameway as the impulse contact of the vdial of the calling subscriber. Inorder to understand the switching arrangements of the exchange groupselector those conditions can for instance be studied, which take placewhen the impulse transmitting device of the register transmits the iirstseries of impulses. This'series corresponds for instance to the digit 2(3 impulses). In order to understand the switching it will be convenientto study the conditions at the beginning and the end of each impulse.

The 4first impulse starts-R10 is demagnetized on account of the openingof the impulse contact 1R2. STMO is rnagnetizedv (plus, 2R10, 5R11,1R12, 3R13, STMO, minus), whereby 1, 2, A4STM0 are closed and SSTMQ isopened. The closing of ZSTMO magnetizes R13 (plus, 6R11, R13, 4R13,2STM0, minus), which receives holding current (plus, 6R11, R13, 5R13,minus). By the magnetizing of R13, l, 2, 3, 4R13 are opened and 5, SR13closed. The buzzer SU is disconnected.

The first impulse ceases-R10 is magnetized by the closing of 1R2. S'IMoreceives holding current in series with R14 whichv ismagnetized (plus,6R11, BRS, 4R14, R14, 1STE/I1, 4ST1\40,'STM0, minus) When the rstimpulse ceases, R10, R11, R12, R13, R14 and S'IMo are magnetized, R12 onaccount of its delayed action.

The second impulse starts-R10 is demagnetized on account of the opening`of thefimpulse contact 1R2. STM1 is magnetized (plus, 2R10, 5R11, 1R12,2R14, ISTMO, STM1, minus), whereby l, 2, BSTR/ f1 are closed and 4STM1is opened. The opening of 4STM1, however, does not demagnetize R11,because this relay has holding current (plus, 6R11, TR2, 3R10, 5R14,minus). STMo is, however, demagnetized upon the opening of 4STM1.

The second impulse ceases- R10 is magnetized upon the closing of 1R2,whereby 1R10 is closed and 2, 3R10 are opened. The opening of 3R10demagnetizes R14, whereby 1, 4, 6R14 are closed and 2, 3, 5R14 areopened. STM1 gets holding current over (plus, 6R11, SRs, 3STM2, 2S'I'M1,STM1, minus).

After the end of the second impulse R10, R11, R12, R13 and STM1 aremagnetized, R12 on account of its delayed action.

The third impulse starts-R10 is demagnetized on account of the openingof the impulse contact 1R2. STM2 is magnetized (plus, 2R10, 5R11,

1R12, 1R14, 1sTM2,. 11111111s whereby 1, 2, 4sTM-2 'i are closed and3STM2 is opened. VThe opening of 3STM1 demagnetizes STM1.

The third impulse ceuses.-R1o is magnetized upon the closing of 1R2.STM2 receives holding current in series with R14, which is magnetized(plus, 6R11, 8R13, 4R14, R14, 4STM3, 4STM2 minus) When the third impulseceases, R10, R11, R12, R13, R14 and STM2 are thus magnetized, R12 onaccount of its delayed action.

When the series of impulses have been sent out, R12 is demagnetizedafter the time of the delayed action, whereby 1R12 is opened and 2, 3R12are closed. The closing of 3R12 magnetizes BRM and l, 2, 3STM2 areclosed. If the first outgoing line is disengaged, R9 is magnetized,before BRM2 gets time to operate. The circuit of R9 will be (plus, 6R11,R9, 7R11, lBRMa, 1BRM2, 1STM2, the outgoing c-wire not shown, minus).The magnetizing of R9 opens 1, 3R9 and closes 2R11, By opening of IRQ,BRM2 is prevented from magnetizing. The closing of 2R9 causes Ra to bemagnetized (plus, 6R11, ZRQ, Re, min-us), whereby 1, 3, 5, 7, 8, 10H8are opened and2, 4, 6, 9, llRs are closed. The closing of 2, 4R8 causesthe incoming a and b wires to be connected to the corresponding outgoingones over 3, 2STM2. The closing of SRS connects ground to the incomingc-wire, whereby the group selector is busied. The opening of 7, SRSdemagnetizes R14. The closing of QRS causes holding of R8 (plus, 9R15,2R9, Ra, minus). The opening of 1, SRS demagnetizes R10, whereby R11 isdemagnetized and opens 6, 7R11, whereby also R13 and R9 are alsodemagnetized. R9 gets holding current from the succeeding selectorsc-wire, which in the meantime has been connected to ground (plus,c-wire, ISTR/I2, 1BRM2, lBRMs, 3R9, llRs, Rs, minus). When theconnection has been established, Ra and BRM1 are the only relays ofexchange group selector SGV that are magnetized.

After the exchange group selector has been operated by the' iirst seriesof impulses transmitted from the register, the other series of impulsesare transmitted, which will operate the succeeding selector. As soon asthe last two series of impulses have operated a line selector, thecircuit of R1 is automatically opened and R1 is demagnetized, wherebythe register selector ReV and also the register are disconnected and theAwires a and b of the line L are connected to the wires a and b leadingto the exchange group selector SGV.

As will be noticed from the above description, an impulse can betransmitted also from the register to connect those from the exchangegroup selector SGV, which correspond to the STM() magnet.

b. Calls extended over two or more exchange group selectors When, forinstance, the subscriber 288 belonging to the junction exchange K11;calls the subscriber 3075 of the district exchange D22, the switchingwill in general be similar to what has been described under a.

When the first impulse transmitted from the engaged register, has causedconnection to a line leading to the district exchange D22, the contact 3is operated when that line is tested and formed, disengaged, whereuponconnection is obtained to an exchange `group selector of districtexchange D22. Said exchange group selector can not be connected to aregister. Buzzer arrangement is not needed either. Accordingly thearrangements of Fig. l for transforming buzzer tone and the d-wire areunnecessary at exchange group selectors which are used by a call from apreceding exchange group selector. r1`he switching is otherwise similarto that described above.

c. Calls extended over a, direction selector cmd one or several echcmgegroup selectors When, for instance, the subscriber 10, belonging to theterminal exchange A10, calls the subscriber 393 of the junction exchangeKm, the switching will be as follows: When the subscriber 1G lifts histelephone and is connected over nder S10 and a preselector and directionselector RVm to the line selector LV10, dial tone is transmitted. Thesubscriber dials the digit 0, whereby the direction selector RV10 isconnected to a trunk leading to the junction exchange when this line istested and found disengaged, contact 1 is operated establishing aconnection to an exchange group selector. In this case a second dialtone will be transmitted direct from a register and not from theselected exchange group selector, that is, connection to a register overa register selector will be obtained automatically as soon as connectionto an exchange group selector has been obtained. The minus pole isconnected to the Contact 1R11 and the contact 1R13 is connected to thed-wire. As the dial tone buzzer of the exchange group selector does notfunction, it is disconnected. The switching is otherwise similar to thatdescribed above under a.

It will be clear that the invention can be modiiied in several wayswithout departing from the main idea. Thus, for instance, in theterminal exchanges shown, direction selectors RV may be replaced bygroup selectors of the same construction as the exchange group selectorsSGV.

It will also be clear'that connections can be extended over any numberof exchanges in series with registers provided only in even numberexchanges, counted from the terminal exchange.

Having thus described our invention, what we claim is: y

l. In an automatic telephone system, a plurality of full automaticterminal exchanges, and a plurality of iull automatic intermediateexchanges, direction selectors in said terminal exchanges, impulseaccumulating and transmitting registers at said intermediate exchangesonly, subscribers lines terminating at said exchanges, impulsetransmitting dials associated with each v one of saidV lines, and meanscontrolled from said terminal exchanges for actuating said registers toestablish connections between a plurality of exchanges.

2. ln an automatic telephone exchange system according to claim 1,characterized by exchange group selectors in said intermediateexchanges, means responsive to the dialling of the number of a calledsubscriber belonging to the same exchange as the calling subscriber forestablishing a connection with this line, means responsive to thedialling of a direction digit by a line for operatinga said directionselector to connect with 12@ a register, and means responsive to thedialling of a number of the called subscriber belonging to a differentexchange than the calling subscriber for operating said register toestablish a connection to said called subscriber at said diiferentexchange.

3. In an automatic telephone exchange system, a plurality of fullautomatic terminal exchanges, a plurality of full automatic intermediateexchanges, subscribers lines terminating in said exchanges, impulsetransmitting dials associated with each one of said lines, impulseregisters and exchange group selectors in said intermediate exchanges,means controlled by the dialling of a calling subscriber for operatingsaid registers, means controlled by said reters for operating saidexchange group selectors, and means controlled by the dial of a callingsubscriber for operating said exchange group selectors.

4. In an automatic telephone system, a plu- 14o rality of full automaticterminalexchanges, a plurality of full automatic intermediate exchanges,subscribers lines terminating at said exchanges, impulse transmittingdials associated with. each one of said lines, impulse registers andexchange group selectors at said intermediate exchanges, meanscontrolled by said dials for operating said registers, means'controlledby said dials for operating said exchange group selectors, and meansresponsive to the operation of said exchange group selector forconnecting a calling line with said registers.

5. In an automatic telephone exchange system, a plurality of fullautomatic telephone exchanges, a plurality of full automaticintermediate exchang-es, subscribers lines terminating in saidexchanges, impulse transmitting dials associated with each one of saidsubscribers lines, impulse registers and exchange group selectors atsaid intermediate exchanges, means controlled by said dials foroperating exchange group selectors, means controlled by said registersfor operating exchange group selectors, and means responsive to thedialling of a certain digit by a subscriber belonging to an intermediateexchange for connecting with the calling subscribers line saidregisters.

6. In a telephone exchange system, a plurality of full automaticterminal exchanges, a plurality of full automatic intermediateexchanges, subscribers lines terminating at said exchanges, impulsetransmitting dials associated with each one of said lines, exchangegroup selectors at said intermediate exchanges, means for establishing aconnection over said group selectors between a calling and a calledsubscriber belonging to an intermediate exchange, and means forestablishing a connection through said group selectors between a callingsubscriber belonging to an intermediate exchange and a called subscriberbelonging to a different exchange.

7. In a telephone exchange system, a plurality of full automaticterminal and intermediate exchanges, a plurality of lines terminating atsaid exchanges, impulse transmitting dials connected with each one ofsaid lines, exchange group selectors at said intermediate exchanges,means controlled by the dial of a calling subscriber belonging to anexchange for once operating a group selector to establish a connectionwith a called subscriber belonging to the same exchange, and meansresponsive to the operation of the dial of a calling subscriberbelonging to one exchange for twice operating said group selector toestablish connection with a called subscriber belonging to a differentexchange.

8. In a telephone exchange system, a plurality of full automaticterminal exchanges, a plurality of full automatic intermediateexchanges, a plurality of subscribers lines terminating at saidexchanges, impulse transmitting dials associated with each one of saidlines, exchange group selectors and impulse registers at saidintermediate exchanges, means responsive to the dialling of a directiondigit by a subscriber belonging to any exchange to operate a groupselector to connect the calling line with a register, means operativethereupon for restoring to normal the operated group selector, meanscontrolled by said register for actuating said last mentioned groupselecto-r, and means for disconnecting said register from the lastmentioned group selector.

9. In an automatic telephone system, a plurality of full automaticterminal exchanges, a plurality of full automatic intermediateexchanges, a plurality of subscribers lines terminating at saidexchanges, an impulse transmitting dial associated with each line,exchange group selectors and impulse registers at said intermediateexchanges, means for connecting a calling line at one exchange with adistant intermediate exchange, means operative thereupon for actuatingsaid exchange group selectors to connect the calling line at saidregisters, and means responsive to the dialling of a direction digit byanother calling subscriber for actuating said exchange group selectorsfor connecting the last mentioned calling line with said registers.

10. In an automatic telephone system, a plurality of terminal exchanges,a plurality of intermediate exchanges, subscribers lines terminating atsaid exchanges, a calling dial associated with each line, selectorswitches at each exchange, impulse accumulating and transmittingregisters at said intermediate exchanges only, means responsive to thedialling of the number of a called line belonging to the same exchangeas the calling line for operating selectors to interconnect said lineswithout the intervention of said registers, and means operative upon thedialling of the number of the called line belonging to a differentexchange for iirst connecting the calling line with a register and thenactuating said register to operate selectors for extending theconnection to the called line, the dialling number of the last mentionedcalled line consisting of a number designating the register, a numberdesignating the called oice and a number designating the called lineproper.

AXEL HERMAN OLSON. STEN DANIEL VIGREN.

